To Flush Or Not To Flush?

Date: 1/12/2011

When replacing R22 A/C systems with a new R410A system do we really need to flush or clean the old line set if you plan on reusing it? The answer to that is yes, absolutely! For starters, we need to get the old mineral oil out of the line set as the R410A equipment uses POE oil. It’s not just the oil we are worried about as a small amount shouldn’t cause a problem. It’s the sludge, moisture, acid and other contaminants that are in the old line set that are the concern. POE oil is not just a good lubricant but it is also a great solvent! It will quickly remove any contaminants from the old line set and plug up things like TXVs and cap tubes. Using a flush like Rx11 Flush will quickly clean the old line set so it can be safely reused.

For line set clean up a 1lb can of flush will clean 1-2 line sets and a 2 lb can will clean up to 5 line sets. Leftover flush can be saved for the next job. The starter kit includes 1 lb of flush, valve, flush gun and hose to get you started. This makes for an inexpensive alternative to replacing that old line set.

Disconnect the old unit and coil from the line set. Remove any driers or obstructions. Partially crimp or restrict one end of the liquid and suction lines to increase contact time of the Rx11. Always leave the other end of each line completely open for adding Rx11, and to prevent pressure from building up.

Connect only the Rx11 flush gun and house (never use a manifold) to the Rx11 canister. For ½” tubing and smaller (liquid line) use a 20-30 second burst of Rx11 thru each line of 50’ or less. A 60-90 second burst of Rx11 will be required for up to 7/8 tubing (suction line). Follow the flush with dry nitrogen at a setting of 120PSI for maximum cleaning. Catch the flush and debris in a bucket at the restricted end of the lines. Completely disconnect Rx11 canister from lines before pressurizing with nitrogen. The additional flush may be needed if line set is extremely dirty. Evacuation to 500 microns will remove any residual solvent leavening the line set clean and ready to re-use.

Rx11 flush can also be used to clean up the entire system after a compressor burnout or during a system retrofit. The need for multiple oil changes or acid driers may be eliminated.* On most systems, a 1 lb can will clean a 3-4 ton system while a 2 lb can will work for up to a 7 ton system.

*As with any product refer to manufacture for complete instructions and safety precautions before using their products. Only use in well-ventilated area. For further information please visit www.nucalgon.com